New Cosmic Survey

Keeping an eye on the entire Universe is a hard job. Some instruments, like the All Sky Monitor on the Rossi X-ray Timing Explorer (RXTE), are designed to do just that. But even if you're not specifically designed for this job, if you hang around long enough and keep your eyes open, you can eventually cover a lot of territory, so to speak. Using data from another RXTE instrument, the Proportional Counter Array (PCA), astronomers have constructed an
X-ray map of the entire sky. They did this using about 20 million seconds of data taken by the PCA when the satellite was moving between observations. Because RXTE has been in operation for about 8 years it has eventually covered almost the entire sky in these "slew" observations, and the resulting X-ray map of the Universe is shown above. This map covers a higher energy range than the All Sky Monitor and is more sensitive than the best maps previously available (obtained by the HEAO1 X-ray observatory). The plane of our Galaxy is clearly seen, running horizontally along the middle of the image, and the map contains hundreds of clearly detected X-ray sources, including objects inside the Milky Way and beyond.